Nitration of starch to produce nitrostarch is known in the art. Typically, the known processes involve nitration of starch in a solution of nitric acid plus another strong acid such as sulfuric acid, perchloric acid, selenic acid or hydrofluoric acid. Mixed acid systems have been used industrially because they provide the best nitration reaction time, the best yield and the best chemical efficiency. The mixtures of acids are used in order to produce high NO.sub.2.sup.+ concentrations to achieve complete nitration. Sulfuric acid is the most frequently used co-acid with nitric acid because it is highly effective and inexpensive.
Highest concentrations of NO.sub.2.sup.+ are known to occur at essentially equal molar amounts of nitric acid and sulfuric acid. As reported by Urbansky, while a reduction in the amount of nitric acid used results in decreased yields of product, it is not advantageous to decrease the amount of secondary acid, as this results in the increased production of unwanted by-products. In such reactions, starches are nitrated in the presence of the combined acid medium, which results in the production of nitrostarch. Usually these acid mixtures also contain water and, additionally, some water is typically formed during the nitration process. The nitrostarch produced is relatively insoluble in the combined acid medium and can be easily separated by drowning with water. However, prior commercial processes then require the drying of the nitrostarch from the associated water. While this required drying process yields dry nitrostarch, the drying process is expensive. Moreover, handling the resulting dry nitrostarch is quite dangerous. Typically, a small quantity of water is left in the product to reduce the handling hazards of completely dry nitrostarch.
The incorporation of nitrostarch into water-in-oil emulsions by conventional processes requires the separate production of the nitrostarch followed by the separate step of adding the nitrostarch to the emulsion. The production of water-in-oil emulsions and the explosive compositions therefrom and water-gel explosives by such conventional processes is both costly and dangerous because it requires the separate production and drying of the nitrostarch and requires the handling of dried nitrostarch. Thus, there has been a need to provide a process by which nitrostarch can be incorporated into water-in-oil emulsions and the explosives resulting therefrom and water-gel explosives economically and safely.